The invention relates to a method for providing a dried reagent in a microfluidic system as well as to a microfluidic system.
Microfluidic systems have a microfluidic structure at least in sections in which one or several microchambers and/or microcanals are formed. For example, such microfluidic systems are provided as microfluidic testing elements or testing systems with which one or several analytes can be analyzed, for example, in a sample of a body fluid. For this purpose one or several reagents are provided in the microfluidic structure, in particular for a detection reaction with the analyte to be analyzed. The one or several reagents are arranged in the microcanals and/or the microchambers of the microfluidic structure in such a manner that they come in contact with the sample liquid during the application of the sample to be tested on the microfluidic testing element, whereupon a detection reaction usually takes place.
Document WO 93/04195 suggested producing spheres with a reagent for an analysis of a biological sample in that an aqueous solution of the reagent is prepared, drops of the aqueous solution are placed in a cold liquid for freezing and the frozen drops are lyophilized.
Lyophilizing involves a freeze-drying that results in a removal of liquid from the deep-frozen material in the vacuum. During this freezing of the solvent, which usually is water, the solvent evaporates in the frozen state (sublimation drying). In this manner a careful drying and preservation of one or several reagents is possible. The end product of a lyophilization is a frozen mass (lyophilizate) that can also be designated as a porous, stable and dry “lyo-cake”.
Document US 2007/0259348 A1 suggested producing lyophilized pellets that are suitable for being used in a microfluidic system. The lyophilized pellets can contain different biological reagents or microparticles. The pellets are produced in that drops of a reagent solution are placed on a cooled plate where they are frozen, after which a vacuum treatment takes place.